pi-Extended nitrofluorene-1,3-dithiole chromophore: enhancing the photoresponse of holographic materials through the balance of intramolecular chargetransfer and electron affinity

The synthesis, electrochemistry, and electron absorption spectra of the nov el push-pull type acceptor, 9-{[4,5-bis(hexylthio)-1,3-dithiol-2-ylidene]et hylidene}-2,4,5,7-tetranitrofluorene 3 is reported. A bathochromic shift an d increased intensities of intramolecular charge transfer bands (compared t o 1) are well-balanced with the electron affinity of the acceptor, which re sults in a pronounced increase of the photoresponse of carbazole-containing photothermoplastic optical information storage materials in the long wavel ength visible and near infrared regions.